Exhaust-fan



J. VAUGHAN MERRIGK, orrHiLADELPHIA, PENNSYLVANIA.

EXHAUST-FAN.

Specification ofLettersIEatent o. 11,071, dated June 18, 1854.

To all whom t may concern: i

`Be it known that I, J. VAUGHAN MERRICK, of the city` of` Philadelphia and 'State of Pennsylvania, have invented a new and Improved Modeof `Using Exhaust-Fans and I do hereby declare that the following isa full, `cle`ar,wand exact description thereof,

reference being had tou the accompanying drawing and to the let-ters of reference marked thereon, in which- Figure 1 is a. vertical section through the blower and smoke chimney; Fig. 2, a perspectiveview of the blower and chimneyas seen from the front.

When'centrifugal or rotary blowers are used to promote combustion they have been in most instances placed in front of the lire and made to discharge into the ash pit under the grates. This mode of using the blower although very general has several serious evils. The great force with which the air is required `to' be thrown under the grates in order` to overcome the friction of the fuel, and of the` smoke passages, causes an intense local combustion and is very destructive to the boilers. The flame and heat from combustion are not dilfused over the fire surface of theboiler and a diminished efficiency results. Forthese reasons the natural draft is preferred in all cases where it is found suflicient and reliable. But as the natural draft in many cases would not be sufficient, or would be subject to great changes owing to variations in the winds and weather, it has been essayed to obtain the advantages of the natural draft by means of centrifugal exhaust fans. These operate by` producing a partial vacu um in the chimney beyond the fire and thus causing a motion ofthe air through the fuel to supply that vacuum. Such exhaust fans have been heretofore placed in the stack itself. These exhaust fans when so placed were exposed to the intense heat of the gases in the flues. Moreover in cases of accident to a fan so placed it was impossible to get at it for repairs without extinguishing the fires. As the fan filled up the greater part of the section of the chimney, it reduced the natural draft of the chimney greatly and rendered the const-ant use `0f. such an exhaust `fan necessary. Such being the evils resulting from the ordinary mode of employmentof exhaust fans, they have obtained but a very limited use. j

My invention consists in so arranging a" centrifugal exhaustfan that it may `be used f" 1 as an auxiliary to the natural draft,without reducing the natural draft when itis `not in use and greatly adding to it whenit is in use. At`the same `time the injury to the fan from the heated contentsV of the stack i and the `inconvenience of repairing incident to the old exhaust fans is almost en* tirely obviated.

To enable others skilled in the art to make and use my invention I will proceed to describe its construction and mode of operation.

A, B, C, D, Fig. 1, represents a vertical section of the smoke pipe of an ordinary steam vessel. A, B is the line where it conlcentral apertures in its side casing for the entrance of the air at `F and F. It has also anozzle or point of discharge at G. The

fan wheel may be the ordinary fan wheel with its simply transverse vanes or it `may be the Dimpfel or any other improved wheel. The fan' wheel is to be rotated by power -applied to its axle in the ordinary manner. Two trunks or rectangular passages made of sheet iron pass from the lower part of the stack (say about 3 feet above the base of the chimney) and communicate with the central openings F F at the sides of the casing of the fan. These tubes or passages are shown at H, I, and H I Fig. 2. One of them is shown in section at H I, Fig. 1. These passages or tubes convey the smoke and gas from the lower part of the stack into the interior of t-he blower. The nozzle of the blower at Gr discharges into the chimney and is so placed that its axis or line of discharge shall be vertically upward in the vdirection of the axis of the stack, as shown in Fig. l. Two valves are placed in the stack. The relative size and position of these valves are shown by the section in Fig. l.

L M is a large disk valve turning on an axle or stem at K. This stem projects and is operated by a crank outside the chimney.

This valve is of the same section as the interior of the chimney and when placed horizontally completely closes thev chimney as shown by the dottedline L M. The other valve O N is nearly rectangular in its section, it is hung at O and is of sufiicient length and width when hanging in the position O N to cover the passages H and H leading to the sides of the blower. This valve may be elevated by the rod N S to the position N O shown in the drawing, or brought down to the position N O.

Having thus described the construction of the valves and the arrangement of the blower and chimney I proceed to describe the'mode of-operation of these parts. When the Y. lweather is favorable and the natural draft suflicient, the blower E E is disconnected from the machinery and remains at rest.' The valve L M occupies a vertical position `and the valve O N is drawn down to the position O N. The vertical passage through the smoke stack is clear and unobstructed. The access of the smoke through the passages H I and H I is cut olf and combustion in the fire is carried on by natural draft. Whenever it is desired to aid the The fan blower is connected with the machinery and rotated. Under this last arrangement the gases and smoke pass up the stack until they reach the valves L M and O N. The valve O N deflects a portion of the smoke and gases toward the openings discharge through the nozzle at Gr in a direction vertically upward through the stack. The effect of this direction of discharge is to establish a current through the chimney which aids the natural draft along the part of the'chimney not obstructed by the valve O N, so that when the smoke and gases reach the lower edge of thetwo valves two currents are established one (shown by the red arrows) is due to the suction of the blower; the other (shown by black arrows) is due to the natural draft aided by the force of the current discharged from the blower at Gr.

The advantages of my improved arrangement ofL valves and exhaust blower for furnishing an auxiliary draft are that it can lbe easily and completely thrown out of use and the natural draft will be as great as though no blower was attached. Secondly, it can be conveniently repaired when necessary without stopping the engine. i A great diminution in expense will result from its use only at such times as when actually required. l

Having thus`described my invention, I do ,s j

not desire to claim the use of suction blowers for increasing draft in a chimney as this has been long known; but

What I claim and desire to secure bv Letters Patent is- The combined arrangement of the valves L M, N O and the external exhaust blower E E operating in the manner and for the purpose substantially as hereinbefore described.

J. VAUGHAN MERRIGK. Witnesses:

STEPHEN N. SIMMQNS, GEO. HARDING. 

